Device and method for electrostatic discharge protection

ABSTRACT

A device is disclosed herein. The device includes an electrostatic discharge (ESD) protection switch and an ESD driver. The ESD driver is configured to receive a first voltage and a second voltage. When a voltage difference between the first voltage and the second voltage is higher than a first voltage threshold, the ESD driver outputs a first trigger signal to turn on the ESD protection switch. When the voltage difference between the first voltage and the second voltage is lower than a second voltage threshold, the ESD driver outputs a second trigger signal to turn on the ESD protection switch.

RELATED APPLICATIONS

This application claims priority to China Application Serial Number202011208888.X, filed on Nov. 3, 2020, which is herein incorporated byreference in its entirety.

BACKGROUND

Gallium nitride (GaN) based devices have been widely applied incommercial applications, in particular, in high-power applications.However, it is difficult to manufacture an electrostatic discharge (ESD)protection system, which is able to deal with bidirectional ESD current,with the foregoing GaN based devices.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 is a block diagram of an electrostatic discharge (ESD) protectiondevice in accordance with some embodiments.

FIG. 2 is a flow chart of a method for operating the ESD protectiondevice as shown in FIG. 1 in accordance with various embodiments of thepresent disclosure.

FIG. 3 is a flow chart of a method for operating the ESD protectiondevice as shown in FIG. 1 in accordance with various embodiments of thepresent disclosure.

FIG. 4 is a circuit diagram of the ESD protection device as shown inFIG. 1 in accordance with some embodiments.

FIG. 5 is a flow chart of a method for operating the ESD protectiondevice as shown in FIG. 4 in accordance with various embodiments of thepresent disclosure.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

The terms used in this specification generally have their ordinarymeanings in the art and in the specific context where each term is used.The use of examples in this specification, including examples of anyterms discussed herein, is illustrative only, and in no way limits thescope and meaning of the disclosure or of any exemplified term.Likewise, the present disclosure is not limited to various embodimentsgiven in this specification.

Reference is now made to FIG. 1. FIG. 1 is a block diagram of anelectrostatic discharge (ESD) protection device 100 in accordance withsome embodiments.

As illustratively shown in FIG. 1, the ESD protection device 100includes an ESD protection switch 110 and an ESD driver 120. In someembodiments, the ESD protection device 100 is used to protect anelectronic device (not shown) from being damaged, and the protectionmanner will be described in detail in the following paragraphs.

In some embodiments, when an ESD event occurs, the ESD driver 120 of theESD protection device 100 is configured to turn on the ESD protectionswitch 110. Therefore, an overvoltage introduced by an ESD event can beconducted to ground or virtual ground in order to prevent an electronicdevice from being damaged by the above-mentioned overvoltage.

Reference is now made to FIG. 2. FIG. 2 is a flow chart of a method 200for operating the ESD protection device 100 in FIG. 1, in accordancewith various embodiments of the present disclosure. For illustration,the operations of the ESD protection device 100 in FIG. 1 are describedby the method 200.

With reference to the method 200 in FIG. 2, in operation 210, the ESDdriver 120 is configured to receive a voltage V1 and a voltage V2. Insome embodiments, the ESD protection device 100 is implemented in aninput of an electronic device for preventing the electronic device frombeing damaged by an overvoltage which is introduced by an ESD event.Terminals T1, T2 of the ESD driver 120 are configured to receive inputvoltages from power sources such as power supply (not shown) and/orground, and the input voltages are regard as the voltage V1 and thevoltage V2. However, the scope of the disclosure is not intended to belimited in such power sources, and other suitable power sources arewithin the contemplated scope of the present disclosure.

With reference to the method 200 in FIG. 2, in operation 220, when avoltage difference between the voltage V1 and the voltage V2 is higherthan a voltage threshold Vth1, the ESD driver 120 outputs a firsttrigger signal to turn on the ESD protection switch 110. In someembodiments, for preventing an electronic device from being damaged byan overvoltage which is introduced by an ESD event, the voltagethreshold Vth1 is set in advance. The voltage threshold Vth1 is setaccording to actual requirements. For example, if a normal operationvoltage of the electronic device is about 5V (volt), the voltagethreshold Vth1 is set to be about 10V. Therefore, when the overvoltageis higher than the voltage threshold Vth1, and the overvoltage isconduced to ground or virtual ground by the ESD protection switch 110.However, the scope of the disclosure is not intended to be limited insuch threshold (e.g., 10V), and other suitable threshold is within thecontemplated scope of the present disclosure.

In some embodiments, when an ESD event occurs, an overvoltage isgenerated and input into the terminal T1 of the ESD driver 120.Therefore, the voltage difference between the voltage V1 and the voltageV2 is higher than the voltage threshold Vth1, and the ESD driver 120outputs a first trigger signal to turn on the ESD protection switch 110.Subsequently, the overvoltage is conducted to ground or virtual groundby the ESD protection switch 110. Hence, the overvoltage does not inputin the electronic device, and the electronic device will not be damaged.

In various embodiments, when an ESD event occurs, an overvoltage, forexample, 15V, is generated and input into the terminal T1 of the ESDdriver 120. The terminal T1 of the ESD driver 120 receives theovervoltage, and the overvoltage is regard as the voltage V1. Meanwhile,the terminal T2 of the ESD driver 120 is grounded, and the voltage V2 isabout 0V. Therefore, the voltage difference between the voltage V1 andthe voltage V2 is, for example, 15V, and the voltage difference ishigher than the voltage threshold Vth1, for example, 10V. In thiscondition, the ESD driver 120 outputs a first trigger signal to turn onthe ESD protection switch 110. Subsequently, the overvoltage isconducted to ground or virtual ground by the ESD protection switch 110for preventing the electronic device from being damaged. However, thescope of the disclosure is not intended to be limited in suchovervoltage and threshold, and other overvoltage and suitable thresholdare within the contemplated scope of the present disclosure.

With reference to the method 200 in FIG. 2, in operation 230, when avoltage difference between the voltage V1 and the voltage V2 is lowerthan a voltage threshold Vth2, the ESD driver 120 outputs a secondtrigger signal to turn on the ESD protection switch 110. In someembodiments, when an ESD event occurs, an overvoltage is thereforeintroduced and will be input into the terminal T1 or the terminal T2.For preventing an electronic device from being damaged by theovervoltage which is input into the terminal T2 of the ESD driver 120,the voltage threshold Vth2 is set in advance. The voltage threshold Vth2is set according to actual requirements. For example, if a normaloperation voltage of the electronic device is about 5V, the voltagethreshold is set to be about 10V. However, if the overvoltage is inputinto the terminal T2, a voltage difference made by the voltage V1 minusthe voltage V2 is a negative number. Therefore, the voltage thresholdVth2 is set to be about −10V. Hence, when the overvoltage is lower thanthe voltage threshold Vth2, the overvoltage is conduced into ground orvirtual ground by the ESD protection switch 110. However, the scope ofthe disclosure is not intended to be limited in such threshold (e.g.,−10V), and other suitable threshold is within the contemplated scope ofthe present disclosure.

In some embodiments, when an ESD event occurs, an overvoltage isgenerated and input into the terminal T2 of the ESD driver 120.Therefore, the voltage difference made by the voltage V1 minus thevoltage V2 is lower than the voltage threshold Vth2, and the ESD driver120 outputs a second trigger signal to turn on the ESD protection switch110. Subsequently, the overvoltage is conducted to ground or virtualground by the ESD protection switch 110. Hence, the overvoltage does notinput in the electronic device, and the electronic device will not bedamaged.

In some embodiments, when an ESD event occurs, an overvoltage, forexample, 15V, is generated and input into the terminal T2 of the ESDdriver 120. The terminal T2 of the ESD driver 120 receives theovervoltage, and the overvoltage is regard as the voltage V2. Meanwhile,the terminal T1 of the ESD driver 120 is grounded, and the voltage V1 isabout 0V. Therefore, the voltage difference made by the voltage V1 minusthe voltage V2 is, for example, −15V, and the voltage difference islower than the voltage threshold Vth2, for example, −10V. In thiscondition, the ESD driver 120 outputs a second trigger signal to turn onthe ESD protection switch 110. Subsequently, the overvoltage isconducted to ground or virtual ground by the ESD protection switch 110for preventing an electronic device from being damaged. However, thescope of the disclosure is not intended to be limited in suchovervoltage and threshold, and other overvoltage and suitable thresholdare within the contemplated scope of the present disclosure.

In view of the above, when an overvoltage is generated and input intothe terminal T1 of the ESD driver 120 or when an overvoltage isgenerated and input into the terminal T2 of the ESD driver 120, the ESDdriver 120 of the ESD protection device 100 turns on the ESD protectionswitch 110, such that the overvoltage is conducted to ground or virtualground to prevent an electronic device from being damaged. Hence, theESD protection device 100 as shown in FIG. 1 is able to deal withbidirectional ESD current.

Although the terms “first,” “second,” etc., may be used herein todescribe various elements, these elements should not be limited by theseterms. These terms are used to distinguish one element from another. Forexample, a first element could be termed a second element, and,similarly, a second element could be termed a first element, withoutdeparting from the scope of the embodiments. As used herein, the term“and/or” includes any and all combinations of one or more of theassociated listed items.

As illustratively shown in FIG. 1, the ESD driver 120 includes a controlcircuit 121, a trigger circuit 123, a trigger circuit 125, a voltageregulator 127, a voltage regulator 129, a resistor R1, and a resistorR2. The trigger circuit 123 includes an input terminal IN1 and an outputterminal O1. The trigger circuit 125 includes an input terminal IN2 andan output terminal O2.

In some embodiments, the control circuit 121 is coupled to the ESDprotection switch 110. The trigger circuit 123 and the control circuit121 are coupled to each other at a node N1. The trigger circuit 125 andthe control circuit 121 are coupled to each other at a node N2.

As illustratively shown in FIG. 1, the voltage regulator 127 is coupledto the trigger circuit 123 in parallel. The voltage regulator 129 iscoupled to the trigger circuit 125 in parallel. The resistor R1 and thetrigger circuit 123 are coupled to each other at the node N1. Theresistor R2 and the trigger circuit 125 are coupled to each other at thenode N2.

One terminal of the control circuit 121, one terminal of the triggercircuit 123, one terminal of the voltage regulator 127, and one terminalof the resistor R2 are coupled to a terminal T1. The terminal T1 iscoupled to power sources such as power supply or ground.

Another terminal of the control circuit 121, one terminal of the triggercircuit 125, one terminal of the voltage regulator 129, and one terminalof the resistor R1 are coupled to a terminal T2. The terminal T2 iscoupled to power sources such as power supply or ground.

The above discussion merely describes exemplary connections that can bemade in accordance with various alternative embodiments. It isunderstood that such various alternative embodiments are not limited tothe specific connections described above or those shown in FIG. 1.

Reference is now made to FIG. 3. FIG. 3 is a flow chart of a method 300for operating the ESD protection device 100 in FIG. 1, in accordancewith various embodiments of the present disclosure. For illustration,the operations of the ESD protection device 100 in FIG. 1 are describedby the method 300.

With reference to the method 300 in FIG. 3, in operation 310, the inputterminal IN1 of the trigger circuit 123 is configured to receive thevoltage V1, and the input terminal IN2 of the trigger circuit 125 isconfigured to receive the voltage V2. In some embodiments, the ESDprotection device 100 is implemented in an input of an electronic devicefor preventing an electronic device from being damaged by an overvoltagewhich is introduced by an ESD event. The input terminal IN1 of thetrigger circuit 123 and the input terminal IN2 of the trigger circuit125 are configured to receive input voltages from power sources such aspower supply and/or ground, and the input voltages are regard as thevoltage V1 and the voltage V2. However, the scope of the disclosure isnot intended to be limited in such power sources, and other suitablepower sources are within the contemplated scope of the presentdisclosure.

With reference to the method 300 in FIG. 3, in operation 320, when avoltage difference between the voltage V1 and the voltage V2 is higherthan a voltage threshold Vth1, the output terminal O1 of the triggercircuit 123 outputs the first trigger signal to turn on the ESDprotection switch 110. In some embodiments, for preventing an electronicdevice from being damaged by an overvoltage which is introduced by anESD event, the voltage threshold Vth1 is set in advance. The voltagethreshold Vth1 is set according to actual requirements. For example, ifa normal operation voltage of the electronic device is about 5V, thevoltage threshold Vth1 is set to be about 10V. Therefore, when theovervoltage is higher than the voltage threshold Vth1, the outputterminal O1 of the trigger circuit 123 outputs the first trigger signalto turn on the ESD protection switch 110, and the overvoltage isconduced to ground or virtual ground by the ESD protection switch 110.However, the scope of the disclosure is not intended to be limited insuch threshold (e.g., 10V), and other suitable threshold is within thecontemplated scope of the present disclosure.

In some embodiments, the voltage regulator 129 is configured to regulatea voltage of the input terminal IN2 and a voltage of the output terminalO2 to be substantially the same. When an ESD event occurs, the voltagedifference between the voltage V1 and the voltage V2 is higher than thevoltage threshold Vth1, and the voltage regulator 129 is configured toregulate a voltage of the input terminal IN2 and a voltage of the outputterminal O2 to be substantially the same. At this time, voltages at twoterminals of the trigger circuit 125 are substantially the same, and thetrigger circuit 125 does not output any signal. Meanwhile, the outputterminal O1 of the trigger circuit 123 outputs the first trigger signalto the control circuit 121 in response to an ESD event. Subsequently,the control circuit 121 turns on the ESD protection switch 110 accordingto the first trigger signal. Therefore, the overvoltage is conducted toground or virtual ground by the ESD protection switch 110 for preventingan electronic device from being damaged.

With reference to the method 300 in FIG. 3, in operation 330, when thevoltage difference between the voltage V1 and the voltage V2 is lowerthan the voltage threshold Vth2, the output terminal O2 of the triggercircuit 125 outputs the second trigger signal to turn on the ESDprotection switch 110. In some embodiments, when an ESD event occurs, anovervoltage is therefore introduced and will be input into the terminalT1 or the terminal T2. For preventing an electronic device from beingdamaged by the overvoltage which is input into the terminal T2, thevoltage threshold Vth2 is set in advance. The voltage threshold Vth2 isset according to actual requirements. For example, if a normal operationvoltage of the electronic device is about 5V, the voltage threshold isset to be about 10V. However, if the overvoltage is input into theterminal T2, a voltage difference made by the voltage V1 minus thevoltage V2 is a negative number. Therefore, the voltage threshold Vth2is set to be about −10V. Hence, when the overvoltage is lower than thevoltage threshold Vth2, the output terminal O2 of the trigger circuit125 outputs the second trigger signal to turn on the ESD protectionswitch 110, and the overvoltage is conduced into ground or virtualground by the ESD protection switch 110. However, the scope of thedisclosure is not intended to be limited in such threshold (e.g., −10V),and other suitable threshold is within the contemplated scope of thepresent disclosure.

In some embodiments, the voltage regulator 127 is configured to regulatea voltage of the input terminal IN1 and a voltage of the output terminalO1 to be substantially the same. When an ESD event occurs, the voltagedifference between the voltage V1 and the voltage V2 is lower than thevoltage threshold Vth2, and the voltage regulator 127 is configured toregulate a voltage of the input terminal IN1 and a voltage of the outputterminal O1 to be substantially the same. At this time, voltages at twoterminals of the trigger circuit 123 are substantially the same, and thetrigger circuit 123 does not output any signal. Meanwhile, the outputterminal O2 of the trigger circuit 125 outputs the second trigger signalto the control circuit 121 in response to an ESD event. Subsequently,the control circuit 121 turns on the ESD protection switch 110 accordingto the second trigger signal. Therefore, the overvoltage is conducted toground or virtual ground by the ESD protection switch 110 for preventingan electronic device from being damaged.

FIG. 4 is a circuit diagram of the ESD protection device 100 as shown inFIG. 1 in accordance with some embodiments.

As illustratively shown in FIG. 4, the ESD protection switch 110includes a ESD protection transistor SW, and the control circuit 121includes a transistor M1 and a transistor M2. The transistor M1 and thetransistor M2 are coupled to each other in series, and one terminal ofthe transistor M1 and one terminal of the transistor M2 are coupled at anode N3. The node N3 is coupled to a control terminal of the ESDprotection transistor SW. Another terminal of the transistor M1 iscoupled to the terminal T1, and another terminal of the transistor M2 iscoupled to the terminal T2.

The trigger circuit 123 includes at least one transistor D11. Oneterminal of the transistor D11 and a control terminal of the transistorD11 are coupled to the terminal T1. Another terminal of the transistorD11 is coupled to the node N1, and the node N1 is coupled to a controlterminal of the transistor M1. However, the scope of the disclosure isnot intended to be limited in implementing the trigger circuit 123 bytransistors, and implementing the trigger circuit 123 by other suitableelectrical elements is within the contemplated scope of the presentdisclosure. In some embodiments, one terminal of the resistor R1 iscoupled to the node N1, and another terminal of the resistor R1 iscoupled to the terminal T2.

Reference is now made to FIG. 4, the voltage regulator 127 includes apull down circuit. The pull down circuit 127 is coupled to the triggercircuit 123 in parallel.

In some embodiments, the pull down circuit 127 includes a transistor M3and a transistor M4. One terminal of the transistor M3 is coupled to theterminal T1, a control terminal of the transistor M3 is coupled to thenode N2, and another terminal of the transistor M3 is coupled to oneterminal of the transistor M4. Another terminal of the transistor M4 iscoupled to the node N1, and a control terminal of the transistor M4 iscoupled to the terminal T2.

As illustratively shown in FIG. 4, the trigger circuit 125 includes atleast one transistor D21. One terminal of the transistor D21 and acontrol terminal of the transistor D21 are coupled to the terminal T2.Another terminal of the transistor D21 is coupled to the node N2, andthe node N2 is coupled to a control terminal of the transistor M2.However, the scope of the disclosure is not intended to be limited inimplementing the trigger circuit 125 by transistors, and implementingthe trigger circuit 125 by other suitable electrical elements is withinthe contemplated scope of the present disclosure. In some embodiments,one terminal of the resistor R2 is coupled to the node N2, and anotherterminal of the resistor R2 is coupled to the terminal T1.

Reference is now made to FIG. 4, the voltage regulator 129 includes apull down circuit. The pull down circuit 129 is coupled to the triggercircuit 125 in parallel.

In some embodiments, the pull down circuit 129 includes a transistor M5and a transistor M6. One terminal of the transistor M6 is coupled to theterminal T2, a control terminal of the transistor M6 is coupled to thenode N1, and another terminal of the transistor M6 is coupled to oneterminal of the transistor M5. Another terminal of the transistor M5 iscoupled to the node N2, and a control terminal of the transistor M5 iscoupled to the terminal T1.

In some embodiments, the above-mentioned transistor includes a BipolarJunction Transistor (BJT), a Metal Oxide Semiconductor Field EffectTransistor (MOSFET), or an Insulated Gate Bipolar Transistor (IGBT).

The above discussion merely describes exemplary connections that can bemade in accordance with various alternative embodiments. It isunderstood that such various alternative embodiments are not limited tothe specific connections described above or those shown in FIG. 4.

Reference is now made to FIG. 5. FIG. 5 is a flow chart of a method 500for operating the ESD protection device 100 in FIG. 4, in accordancewith various embodiments of the present disclosure. For illustration,the operations of the ESD protection device 100 in FIG. 4 are describedby the method 500.

With reference to the method 500 in FIG. 5, in operation 510, oneterminal of the transistor D11 is configured to receive the voltage V1,and one terminal of the transistor D21 is configured to receive thevoltage V2. In some embodiments, the ESD protection device 100 isimplemented in an input of an electronic device for preventing anelectronic device from being damaged by an overvoltage which isintroduced by an ESD event. The transistor D11 of the trigger circuit123 and the transistor D21 of the trigger circuit 125 are configured toreceive input voltages from power sources such as power supply and/orground, and the input voltages are regard as the voltage V1 and thevoltage V2. However, the scope of the disclosure is not intended to belimited in such power sources, and other suitable power sources arewithin the contemplated scope of the present disclosure.

With reference to the method 500 in FIG. 5, in operation 520, thetransistor D11 of the trigger circuit 123 is configured to output afirst trigger signal to turn on the transistor M1 of the control circuit121 according to the voltage V1, such that the transistor M1 of thecontrol circuit 121 transmits the voltage V1 to the control terminal ofthe ESD protection transistor SW for turning on the ESD protectiontransistor SW.

In some embodiments, the transistor D11 of the trigger circuit 123outputs the first trigger signal according to the voltage V1 and athreshold voltage Vth1 of the transistor D11. In some embodiments, forpreventing an electronic device from being damaged by an overvoltagewhich is introduced by an ESD event, the voltage threshold Vth1 is setin advance. The voltage threshold Vth1 is set according to actualrequirements. For example, if a normal operation voltage of theelectronic device is about 5V, the voltage threshold Vth1 is set to beabout 10V. In order to set the voltage threshold Vth1 to be about 10V,multiple transistors are coupled to each other in series. For example,the threshold of each of the transistors is 2V, and five transistorscoupled to each other in series can provide a threshold about 10V. Asillustratively shown in FIG. 4, the trigger circuit 123 includes aplurality of transistors D11-D1 n coupled to each other in series. Ifthe threshold of each of the plurality of transistors D11-D1 n is 2V,the trigger circuit 123 may include five of plurality of transistorsD11-D1 n, and the voltage threshold Vth1 of the trigger circuit 123 isabout 10V. However, the scope of the disclosure is not intended to belimited in such threshold (e.g., 10V), and other suitable threshold iswithin the contemplated scope of the present disclosure.

In various embodiments, when an ESD event occurs, an overvoltage, forexample, 15V, is generated and input into the terminal T1 of the ESDdriver 120. If the overvoltage is higher than the voltage thresholdVth1, for example, 10V, of the transistors D11-D1 n of the triggercircuit 123, the transistors D11-D1 n of the trigger circuit 123 areconfigured to output a first trigger signal to turn on the transistor M1of the control circuit 121. Subsequently, the voltage V1 is transmittedto the control terminal of the ESD protection transistor SW by thetransistor M1. Therefore, the ESD protection transistor SW is turned onby the voltage V1, and the overvoltage is conduced to ground or virtualground by the ESD protection transistor SW. However, the scope of thedisclosure is not intended to be limited in such overvoltage andthreshold, and other overvoltage and suitable threshold are within thecontemplated scope of the present disclosure.

In some embodiments, when an overvoltage, for example, 15V, is generatedand input into the terminal T1 of the ESD driver 120 in response to anESD event, the transistor M5 is turned on according to the voltage V1from the terminal T1 and the transistor M6 is turned on according to thevoltage V1 transmitted by the trigger circuit 123 from the terminal T1to the node N1. Therefore, both of the transistor M5 and transistor M6of the pull down circuit 129 are turned on, and a voltage across thetrigger circuit 125 is pulled down to the terminal T2. Hence, thetrigger circuit 125 does not output any signal.

With reference to the method 500 in FIG. 5, in operation 530, thetransistor D21 of the trigger circuit 125 is configured to output asecond trigger signal to turn on the transistor M2 of the controlcircuit 121 according to the voltage V2, such that the transistor M2 ofthe control circuit 121 transmits the voltage V2 to the control terminalof the ESD protection transistor SW for turning on the ESD protectiontransistor SW.

In some embodiments, the transistor D21 of the trigger circuit 125outputs the second trigger signal according to the voltage V2 and athreshold voltage Vth2 of the transistor D21. In some embodiments, forpreventing an electronic device from being damaged by an overvoltagewhich is introduced by an ESD event, the voltage threshold Vth2 is setin advance. The voltage threshold Vth2 is set according to actualrequirements. For example, if a normal operation voltage of theelectronic device is about 5V, the voltage threshold Vth2 is set to beabout 10V. In order to set the voltage threshold Vth2 to be about 10V,multiple transistors are coupled to each other in series. For example,the threshold of each of the transistors is 2V, and five transistorscoupled to each other in series can provide a threshold about 10V. Asillustratively shown in FIG. 4, the trigger circuit 125 includes aplurality of transistors D21-D2 n coupled to each other in series. Ifthe threshold of each of the plurality of transistors D21-D2 n is 2V,the trigger circuit 125 may include five of plurality of transistorsD21-D2 n, and the voltage threshold Vth2 of the trigger circuit 125 isabout 10V. However, the scope of the disclosure is not intended to belimited in such threshold (e.g., 10V), and other suitable threshold iswithin the contemplated scope of the present disclosure.

In various embodiments, when an ESD event occurs, an overvoltage, forexample, 15V, is generated and input into the terminal T2 of the ESDdriver 120. If the overvoltage is higher than the voltage thresholdVth2, for example, 10V, of the transistors D21-D2 n of the triggercircuit 125, the transistors D21-D2 n of the trigger circuit 125 areconfigured to output a second trigger signal to turn on the transistorM2 of the control circuit 121. Subsequently, the voltage V2 istransmitted to the control terminal of the ESD protection transistor SWby the transistor M2. Therefore, the ESD protection transistor SW isturned on by the voltage V2, and the overvoltage is conduced to groundor virtual ground by the ESD protection transistor SW. However, thescope of the disclosure is not intended to be limited in suchovervoltage and threshold, and other overvoltage and suitable thresholdare within the contemplated scope of the present disclosure.

In some embodiments, when an overvoltage, for example, 15V, is generatedand input into the terminal T2 of the ESD driver 120 in response to anESD event, the transistor M3 is turned on according to the voltage V2transmitted by the trigger circuit 125 from the terminal T2 to the nodeN2 and the transistor M4 is turned on according to the voltage V2 fromthe terminal T2. Therefore, both of the transistor M3 and transistor M4of the pull down circuit 127 are turned on, and a voltage across thetrigger circuit 123 is pulled down to the terminal T1. Hence, thetrigger circuit 123 does not output any signal.

In view of the above, when an overvoltage, for example, 15V, inputs intothe terminal T1 or the terminal T2 of the ESD protection device 100, theESD protection device 100 turns on the ESD protection transistor SW,such that the overvoltage is conducted from the terminal T1 or theterminal T2 to ground to prevent an electronic device from beingdamaged. Hence, the ESD protection device 100 as shown in FIG. 4 is ableto deal with bidirectional ESD current.

Also disclosed is a device. The device includes an ESD protection switchand an ESD driver. The ESD driver is configured to receive a firstvoltage and a second voltage. When a voltage difference between thefirst voltage and the second voltage is higher than a first voltagethreshold, the ESD driver outputs a first trigger signal to turn on theESD protection switch. When the voltage difference between the firstvoltage and the second voltage is lower than a second voltage threshold,the ESD driver outputs a second trigger signal to turn on the ESDprotection switch.

In some embodiments, the ESD driver includes a first trigger circuit.The first trigger circuit includes a first input terminal and a firstoutput terminal. The first input terminal of the first trigger circuitis configured to receive the first voltage. When the voltage differencebetween the first voltage and the second voltage is higher than thefirst voltage threshold, the first output terminal of the first triggercircuit outputs the first trigger signal.

In various embodiments, the ESD driver includes a second triggercircuit. The second trigger circuit includes a second input terminal anda second output terminal. The second input terminal of the secondtrigger circuit is configured to receive the second voltage. When thevoltage difference between the first voltage and the second voltage islower than the second voltage threshold, the second output terminal ofthe second trigger circuit outputs the second trigger signal.

In some embodiments, the ESD driver further includes a first voltageregulator. The first voltage regulator is coupled to the first triggercircuit in parallel, and configured to regulate a voltage of the firstinput terminal and a voltage of the first output terminal to besubstantially the same.

In various embodiments, the ESD driver further includes a second voltageregulator. The second voltage regulator is coupled to the second triggercircuit in parallel, and configured to regulate a voltage of the secondinput terminal and a voltage of the second output terminal to besubstantially the same.

In some embodiments, when the voltage difference between the firstvoltage and the second voltage is higher than the first voltagethreshold, the second voltage regulator is configured to regulate avoltage of the second input terminal and a voltage of the second outputterminal to be substantially the same, and the first output terminaloutputs the first trigger signal to turn on the ESD protection switch.

In various embodiments, when the voltage difference between the firstvoltage and the second voltage is lower than the second voltagethreshold, the first voltage regulator is configured to regulate avoltage of the first input terminal and a voltage of the first outputterminal to be substantially the same, and the second output terminaloutputs the second trigger signal to turn on the ESD protection switch.

Also disclosed is a device. The device includes an ESD protectiontransistor and an ESD driver. The ESD driver includes a firsttransistor, a second transistor, a first trigger circuit, and a secondtrigger circuit. The first transistor is configured to receive a firstvoltage. The second transistor is coupled to the first transistor at anode which is coupled to a control terminal of the ESD protectiontransistor, and configured to receive a second voltage. The firsttrigger circuit is configured to output a first trigger signal to turnon the first transistor according to the first voltage, such that thefirst transistor transmits the first voltage to the control terminal ofthe ESD protection transistor. The second trigger circuit is configuredto output a second trigger signal to turn on the second transistoraccording to the second voltage, such that the second transistortransmits the second voltage to the control terminal of the ESDprotection transistor.

In some embodiments, the first trigger circuit includes at least onetransistor, and the first trigger circuit outputs the first triggersignal according to the first voltage and a threshold voltage of the atleast one transistor.

In various embodiments, when a voltage difference between the firstvoltage and the second voltage is higher than the threshold voltage ofthe at least one transistor, the first trigger circuit outputs the firsttrigger signal.

In some embodiments, the second trigger circuit includes at least onetransistor, and the second trigger circuit outputs the second triggersignal according to the second voltage and a threshold voltage of the atleast one transistor.

In various embodiments, when a voltage difference between the firstvoltage and the second voltage is lower than the threshold voltage ofthe at least one transistor, the second trigger circuit outputs thesecond trigger signal.

In some embodiments, the ESD driver further includes a first pull downcircuit. The first pull down circuit is coupled to the first triggercircuit in parallel, and configured to pull down a voltage across thefirst trigger circuit.

In various embodiments, the ESD driver further includes a second pulldown circuit, and the second pull down circuit is coupled to the secondtrigger circuit in parallel, and configured to pull down a voltageacross the second trigger circuit.

Also disclosed is a method. The method includes: outputting a firsttrigger signal to turn on an ESD protection switch when a voltagedifference between a first voltage and a second voltage is higher than afirst voltage threshold; and outputting a second trigger signal to turnon the ESD protection switch when the voltage difference between thefirst voltage and the second voltage is lower than a second voltagethreshold.

In some embodiments, outputting the first trigger signal to turn on theESD protection switch when the voltage difference between the firstvoltage and the second voltage is higher than the first voltagethreshold includes: outputting the first trigger signal by a firstoutput terminal of a first trigger circuit when the voltage differencebetween the first voltage and the second voltage is higher than thefirst voltage threshold of at least one first transistor of the firsttrigger circuit.

In various embodiments, outputting the second trigger signal to turn onthe ESD protection switch when the voltage difference between the firstvoltage and the second voltage is lower than the second voltagethreshold includes: outputting the second trigger signal by a secondoutput terminal of a second trigger circuit when the voltage differencebetween the first voltage and the second voltage is lower than thesecond voltage threshold of at least one second transistor of the secondtrigger circuit.

In some embodiments, the method further includes: pulling down a voltageacross the first trigger circuit; and pulling down a voltage across thesecond trigger circuit.

In various embodiments, pulling down a voltage across the second triggercircuit includes: pulling down a voltage across the second triggercircuit when the voltage difference between the first voltage and thesecond voltage is higher than the first voltage threshold.

In some embodiments, pulling down a voltage across the second triggercircuit includes: pulling down a voltage across the second triggercircuit when the voltage difference between the first voltage and thesecond voltage is lower than the first voltage threshold.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A device, comprising: an electrostatic discharge(ESD) protection switch; and an ESD driver configured to receive a firstvoltage at a first terminal and receive a second voltage at a secondterminal; wherein when the first voltage received at the first terminalis a first overvoltage and a voltage difference between the firstvoltage and the second voltage is higher than a first voltage threshold,the ESD driver outputs a first trigger signal to turn on the ESDprotection switch; wherein when the second voltage received at thesecond terminal is a second overvoltage and the voltage differencebetween the first voltage and the second voltage is lower than a secondvoltage threshold, the ESD driver outputs a second trigger signal toturn on the ESD protection switch.
 2. The device of claim 1, wherein theESD driver comprises: a first trigger circuit, comprising: a first inputterminal configured to receive the first voltage; and a first outputterminal, wherein when the voltage difference between the first voltageand the second voltage is higher than the first voltage threshold, thefirst output terminal outputs the first trigger signal.
 3. The device ofclaim 2, wherein the ESD driver further comprises: a second triggercircuit, comprising: a second input terminal configured to receive thesecond voltage; and a second output terminal, wherein when the voltagedifference between the first voltage and the second voltage is lowerthan the second voltage threshold, the second output terminal outputsthe second trigger signal.
 4. The device of claim 3, wherein the ESDdriver further comprises: a first voltage regulator coupled to the firsttrigger circuit in parallel, and configured to regulate a voltage of thefirst input terminal and a voltage of the first output terminal to besubstantially the same.
 5. The device of claim 4, wherein the ESD driverfurther comprises: a second voltage regulator coupled to the secondtrigger circuit in parallel, and configured to regulate a voltage of thesecond input terminal and a voltage of the second output terminal to besubstantially the same.
 6. The device of claim 5, wherein when thevoltage difference between the first voltage and the second voltage ishigher than the first voltage threshold, the second voltage regulator isconfigured to regulate a voltage of the second input terminal and avoltage of the second output terminal to be substantially the same, andthe first output terminal outputs the first trigger signal to turn onthe ESD protection switch.
 7. The device of claim 6, wherein when thevoltage difference between the first voltage and the second voltage islower than the second voltage threshold, the first voltage regulator isconfigured to regulate a voltage of the first input terminal and avoltage of the first output terminal to be substantially the same, andthe second output terminal outputs the second trigger signal to turn onthe ESD protection switch.
 8. A device, comprising: an ESD protectiontransistor; and an ESD driver, comprising: a first transistor configuredto receive a first voltage; a second transistor coupled to the firsttransistor at a node which is coupled to a control terminal of the ESDprotection transistor, and configured to receive a second voltage; afirst trigger circuit configured to output a first trigger signal toturn on the first transistor according to the first voltage, such thatthe first transistor transmits the first voltage to the control terminalof the ESD protection transistor; and a second trigger circuitconfigured to output a second trigger signal to turn on the secondtransistor according to the second voltage, such that the secondtransistor transmits the second voltage to the control terminal of theESD protection transistor.
 9. The device of claim 8, wherein the firsttrigger circuit comprises at least one transistor, the first triggercircuit outputs the first trigger signal according to the first voltageand a threshold voltage of the at least one transistor.
 10. The deviceof claim 9, wherein when a voltage difference between the first voltageand the second voltage is higher than the threshold voltage of the atleast one transistor, the first trigger circuit outputs the firsttrigger signal.
 11. The device of claim 8, wherein the second triggercircuit comprises at least one transistor, the second trigger circuitoutputs the second trigger signal according to the second voltage and athreshold voltage of the at least one transistor.
 12. The device ofclaim 11, wherein when a voltage difference between the first voltageand the second voltage is lower than the threshold voltage of the atleast one transistor, the second trigger circuit outputs the secondtrigger signal.
 13. The device of claim 8, wherein the ESD driverfurther comprises: a first pull down circuit coupled to the firsttrigger circuit in parallel, and configured to pull down a voltageacross the first trigger circuit.
 14. The device of claim 13, whereinthe ESD driver further comprises: a second pull down circuit coupled tothe second trigger circuit in parallel, and configured to pull down avoltage across the second trigger circuit.
 15. A method, comprising:outputting a first trigger signal to turn on an ESD protection switchwhen a first voltage received at a first terminal is a first overvoltageand a voltage difference between the first voltage received at the firstterminal and a second voltage received at a second terminal is higherthan a first voltage threshold; and outputting a second trigger signalto turn on the ESD protection switch when the second voltage at thesecond terminal is a second overvoltage and the voltage differencebetween the first voltage received at the first terminal and the secondvoltage received at the second terminal is lower than a second voltagethreshold.
 16. The method of claim 15, wherein outputting the firsttrigger signal to turn on the ESD protection switch when the voltagedifference between the first voltage and the second voltage is higherthan the first voltage threshold comprises: outputting the first triggersignal by a first output terminal of a first trigger circuit when thevoltage difference between the first voltage and the second voltage ishigher than the first voltage threshold of at least one first transistorof the first trigger circuit.
 17. The method of claim 16, whereinoutputting the second trigger signal to turn on the ESD protectionswitch when the voltage difference between the first voltage and thesecond voltage is lower than the second voltage threshold comprises:outputting the second trigger signal by a second output terminal of asecond trigger circuit when the voltage difference between the firstvoltage and the second voltage is lower than the second voltagethreshold of at least one second transistor of the second triggercircuit.
 18. The method of claim 17, further comprising: pulling down avoltage across the first trigger circuit; and pulling down a voltageacross the second trigger circuit.
 19. The method of claim 18, whereinpulling down a voltage across the second trigger circuit comprises:pulling down a voltage across the second trigger circuit when thevoltage difference between the first voltage and the second voltage ishigher than the first voltage threshold.
 20. The method of claim 19,wherein pulling down a voltage across the second trigger circuitcomprises: pulling down a voltage across the second trigger circuit whenthe voltage difference between the first voltage and the second voltageis lower than the second voltage threshold.